living with the lab
Using Your Arduino,
Breadboard and Multimeter
Work in teams of two!
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© 2012 David Hall
living with the lab
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The content of this presentation is for informational purposes only and is intended only for students
attending Louisiana Tech University.
The author of this information does not make any claims as to the validity or accuracy of the information
or methods presented.
Any procedures demonstrated here are potentially dangerous and could result in injury or damage.
Louisiana Tech University and the State of Louisiana, their officers, employees, agents or volunteers, are
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materials or ideas, or from your performing the experiments or procedures depicted in this presentation.
If you do not agree, then do not view this content.
The copyright label, the Louisiana Tech logo, and the “living with the lab” identifier should not be removed
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You may modify this work for your own purposes as long as attribution is clearly provided.
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living with the lab
Your Multimeter
pincer clips – good for working
with robot wiring
probes
(push these onto probes)
leads
turn knob to what you
would like to measure
You will use the multimeter to understand and troubleshoot circuits, mostly
measuring DC voltage, resistance and DC current.
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living with the lab
The Arduino Duemilanove (older version of the Uno)
14 digital I/O pins
(I/O = input / output)
USB cable plug
on-board voltage
regulator
external power plug
power pins
Power can be provided through the USB cable (+5V from
the computer) or externally (7-12V supply recommended)
microcontroller
analog input pins
(the brains)
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living with the lab
Measure Vin
Vin will be the same as your power supply voltage. The battery pack here has
8 AA batteries, resulting in approximately 12V (11.68V was measured)
Vin = power supply voltage
switch to DC Volts
Gnd = ground (negative)
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living with the lab
Check Voltage at 5V Power Pin
The on-board voltage regulator reduces the voltage from Vin down to about 5V
5V = power from on-board
voltage regulator
Gnd = ground (negative)
Notice that the regulated voltage
is very close to the “target” of 5V
switch to DC Volts
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living with the lab
Check Voltage at 3V3 Pin
The Arduino also has an on-board voltage regulator that outputs 3.3V.
3.3V = power from USB chip
Gnd = ground (negative)
If you ever need less than 5V
for a project, you can use this
pin. The current that you can
draw from this pin is limited to
50mA.
max power = V∙I
= 3.3V∙0.05A
= 0.165W
= 165mW
switch to DC Volts
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living with the lab
Select Resistors
Find the 470W and the 10kW resistors from your parts kit.
color
digit
black
0
brown
1
red
2
orange
3
yellow
4
green
5
blue
6
violet
7
gray
8
white
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gold = ±5%
first
digit
second
digit
tolerance
silver = ±20%
number
of zeros
Example: 470W resistor:
4 = yellow
7 = violet
Add 1 zero to 47 to make 470, so 1 = brown
So, 470 = yellow, violet, brown
Now, find the 10kW resistor.
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living with the lab
Check Resistance of Resistors
R ~ 470W
470W resistor
set multimeter
to measure W
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living with the lab
LEDs (Light Emitting Diodes)
+
-
electronic symbol
Diagram from Wikipedia description of an LED
Electricity can only flow one way through an LED (or any diode).
The flat spot on the LED must be connected to ground (GND).
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living with the lab
Building an LED Circuit
Supplies:
•
•
•
•
2 wires – cut a little longer than the jumper wires
that come with your kit and strip the ends
LED
470W resistor
battery pack (or you can power the system using
the USB cable from your computer)
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living with the lab
Building an LED Circuit
(the next slide explains how the breadboard works)
short leg of LED connects
to ground wire
red wire to +5V supply
green wire to Gnd
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living with the lab
Breadboarding
the two sides
are not connected
these pins are
connected
these pins are
not connected
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living with the lab
The Circuit
470W
+
5V
-
5V
470W
these circuit diagrams
are equivalent
symbol for ground (Gnd)
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living with the lab
Replace the 470 W Resistor with the 10kW Resistor
What happens and Why??
ANSWER: The smaller resistor (470W) provides less resistance to current than
the larger resistor (10kW). Since more current passes through the smaller
resistor, more current also passes through the LED making it brighter.
What would happen if you forgot to put in a resistor? You would probably burn
up your LED.
The End 
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